


The Perks of a Brilliant Bet.

by camikingst



Category: Harry Potter - J. K. Rowling, Once Upon a Time (TV), Supergirl (TV 2015)
Genre: Alternate Universe - Hogwarts, F/F, F/M, Multi
Language: English
Status: Completed
Published: 2017-03-18
Updated: 2017-03-18
Packaged: 2018-10-07 01:02:26
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,588
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10348929
Author URL: https://archiveofourown.org/users/camikingst/pseuds/camikingst
Summary: Hogwarts AU crossover, (Supergirl/Once Upon a Time) mainly Supercat/SuperCorp and Swan Queen but also some Rumbelle, maybe even a little Sanvers.Emma Swan, Lena Luthor, Kara Danvers and Belle French, are the new female prefects of Hogwarts, all excellent students and the most promising witches of their age, until they start sharing the same Prefect's bedroom and their friendship becomes a pain for professors Mills, Gold and Grant since they get involved in a bet between the girls, that might lead to something else.





	

It was very early in the morning when Emma Swan woke up, she knew this because her head was throbbing, that meant she had not slept enough hours, which lead her to the conclusion that it was sometime before noon, definitely very early in the morning. She growled loudly, hoping that would stop the annoying sound that had disturbed her sleep.

"Swan get up! They are finally here—" Graham exclaimed jumping over her bed in order to get to the door of the reduced trailer they lived in.

"Who are finally here?" She asked half asleep, opening one eye to look at her best friend now opening the door and petting the head of a big gray owl, the animal carried two letters envelopes with him.  
   
"Not who, what!" He corrected enthusiastically, closing the door behind him after giving the bird a treat he easily reached with the length of his arm over the kitchen counter, "congratulations Prefect Swan."

Emma sat up quickly after she put together Graham's words, her eyes wide open and the trace of a smile already forming up on her lips, she pulled one of the letters from her friend's hand.

_Dear Ms. Swan,_

_We are pleased to inform you that you have been selected to serve as Prefect for Gryffindor House. Your school record shows that you have exhibited quick-thinking in stressful situations, the ability to lead others, and the bravery that Gryffindors have long been lauded for._

_We are certain that you will continue to be a model for your peers and will take your new responsibilities seriously. Enclosed please find your Prefect's Badge, which should be worn on your school robes at all times. Congratulations_!

 _Sincerely,_  
_Mary Margaret Blanchard_ _,_  
_Head of Gryffindor House_.

A sneer formed on her face automatically when she read her professor's name, the contempt she felt towards the woman never failed to show on her features.

"Will you ever tell me why you hate Mrs. Blanchard so much Ems?"

"It's not important," she dismissed with one hand as always, "we are prefects G!"

"We are indeed E—. How about some tequila to celebrate?"

"Where will you find tequila? Out there in the forest?"

"I have my ways Swan, but first let's sleep some more it's not even noon yet," he gave her one of his patented 'I know you love me' smiles before he jumped once again over her bed and landed perfectly on his own mattress.

They definitely were in need of a bigger place.

...

"Kara wake up! Your letter is here little monster—, K-A-R-A —," Alex exclaimed non stop, before she hoped and landed heavily over her sister's frame covered  by several layers of blankets like dead weight, the surface of her bed was so padded that Kara barely noticed the disturbance of Alex weight  from beneath the blankets.

"Hm?" She mumbled with her head buried in the pillow.

"The letter, Kara, the one you waited for weeks, but if you are not interested I can always come later—," she started dramatically preparing herself to leave the comfortable surface that was her sister's back, but before she finished talking Kara had jumped of bed throwing her weight off her body, like she was only a feather laying over her bed.

She ripped the envelope from her sister's hands, and devoured the words inside like it was the only thing that was worth reading in the entire universe.

_Dear Ms. Danvers,_

_We are pleased to inform you that you have been selected to serve as Prefect for Hufflepuff House. Your school record shows that you are willing to work hard, have the ability to lead others, and value fair play, which Hufflepuffs have long been lauded for._

_We are certain that you will continue to be a model for your peers and will take your new responsibilities seriously. Enclosed please find your Prefect's Badge, which should be worn on your school robes at all times. Congratulations_!

 _Sincerely,_  
_Regina Mills,_  
_Head of Hufflepuff House_.

"I'm in Alex! I'm in!" Kara exclaimed lifting the redhead from the ground and twirling around the room with holding her in a tight embrace.

"You are, little monster, but I'm also a prefect and I need my ribs intact to continue being one, you know?" She answered short of breath, because of the crushing hug her sister was giving her.

"Sorry!" Kara apologized putting her down slowly, "you okay?"

"Yeah—," she rolled her eyes, "just injured for life, but no worries," she added with a smirk, this time making Kara roll her eyes, " I'm so proud of you baby sister, you will love the prefects special dorms and wait to see the bathroom, it has a giant pool!"

"You didn't tell me that before," Kara complained narrowing eyes.

"I'm telling you now, ain't I?"

"Yeah, one year late! You have been prefect for a whole year Alex—."

"There are books about the castle and it's hidden places in the library, you know? So basically I was not hiding anything from you, " She said without the smallest trace of remorse.

"Is it always about books with you Ravenclaws?" Kara laughed.

"Mostly," Alex winked.

...

"Here you go love, enjoy it," Belle said handing a book to an eight year old girl from a high shelf on the wall.

"Thank you Ms." The girl answered running towards the till to pay for it.

She worked for her father at Flourish and Blotts, during the school break and honestly she didn't mind at all. She loved the place, the smell of books and the shine in the children's eyes, when they received a new book and held on to it, thrilled and willing to learn some magic.

The ladder she had climbed up to reach the book suddenly moved right and she was forced to hold on to it, in order not to fall, when the sudden movement stopped she rushed to climb down, in case they started moving once again, but when she climbed one step down, the stairs moved once again and she fell off the structure.

She waited for the blow, but it never came, she instead descended softly on somebody's arms. Except it wasn't just somebody. It was Mr. Gold. Professor Gold, head of Ravenclaw House. It was his arms lifting her now.

"Thank you —," she whispered with her blue eyes fixed on his, "thank you," she repeated, her words were barely audible and her gaze was drilling its way into his usually apathetic expression.

He put her down with a frown.

"No matter," he answered moving his hands dismissively and taking a step back.

She was trying to think of something to say, something intelligent, anything, when a letter flew through the door's letter box  
and landed on her hands.

Her eyes went wide when she realized what it was, she was so surprised that she completely forgot about the man in front of her as she opened it.

_Dear Ms. French,_

_We are pleased to inform you that you have been selected to serve as Prefect for Ravenclaw House. Your school record shows that you have exhibited creativity, the ability to lead others, and the wit that Ravenclaws have long been lauded for._

_We are certain that you will continue to be a model for your peers and will take your new responsibilities seriously. Enclosed please find your Prefect's Badge, which should be worn on your school robes at all times. Congratulations_!

_Sincerely,_  
_Professor_ _R_ _._ _Gold._  
_Head of Ravenclaw House._

Belle looked up again with a big smile printed on her lips, right before she started giggling.

"Why the owl, if you were coming here anyways professor Gold?" She asked still laughing with an arched eyebrow.

"That's why I prefer crows, stupid slow creatures those owls," he simply said folding his arms over his chest, "however, congratulations Ms. French."

"Thank you Professor."

...

"Ms. Luthor? May I come in?" A gentle knock on her bedroom door, followed by the sweet voice of her domestic elf, snapped her out of her thoughts.

She was sitting on her enormous bedroom's cushioned window seat.

"Come in Marcy," she replied sweetly.

"This arrived for you Ms. Luthor," the creature said approaching the window.

"How many times have I asked you to call me Lena, Marcy?"

"Not enough, I'm afraid, Marcy can not  address to a great witch from a great family of pure blood magicians like Ms. Luthor by her first name."

"Marcy I freed you so many years ago, you owe me nothing, much less to my family," Lena rolled her eyes knowing that reasoning with Marcy was impossible and that the elf would never leave her side, unless she ordered her so, "you said something about a package for me," she reminded the elf, extending her hand to receive it.

"A letter Ms. Luthor," she replied handing Lena the envelope.

"Finally, what took you so much Professor Grant?" Lena mumbled to herself, tearing the envelope apart and starting to read the letter out loud for Marcy to hear.

_Dear Ms. Luthor,_

_We are pleased to inform you that you have been selected to serve as Prefect for Slytherin House. Your school record shows that you have ambition, the ability to lead others, and are resourceful, which Slytherins have long been lauded for._

_We are certain that you will continue to be a model for your peers and will take your new responsibilities seriously. Enclosed please find your Prefect's Badge, which should be worn on your school robes at all times. Congratulations_!

 _Sincerely,_  
Catherine Grant _._  
_Head of Slytherin House_.

"Congratulations, Ms. Luthor," Marcy said placing one of her little hands over Lena's shoulder, who has her look lost once again on the mountains behind her window.

"Thank you Marcy," she whispered patting the elf's hand softly with her own.

...

  


The Hogwarts Express left the 9 3/4 platform exactly when the clock marked eleven, one minute after that, two women walked in the crowded cabin where twenty four students waited for the prefects usual reunion.

"Good morning students," the shorter woman started, her blonde hair was perfectly curled in loose waves and her small shape was flawlessly wrapped in a very tight and short muggle green dress.

Many jaws fell to the floor with her sudden appearance, due the way she was dressing. 

Ignoring the murmurs caused by her looks, her ways or her astonishing entrances was one of her mastered specialties. But when the new Slytherin's prefect boy whistled shamelessly, giving a lascive glance to her bare legs and proceeding to stare directly at her breast, he gained one of her famous freezing to the bone glares over her sunglasses. She could not always ignore everything.

"Killian! You are a prefect now, act like one!" The woman beside her scolded with a frown.

Regina hated guys like Killian and that hatred never failed to show on her face when they made something stupid, dangerous or disrespectful. Slytherins never failed to do all of that, sometimes even all of them at the exact same time. If anyone asked her opinion Killian Jones was the worst of them all.

"Now that we have your attention, allow us, to remind you that being a prefect at Hogwarts school of witchcraft and wizardry is not just a privilege, it is a responsibility and you must rise to the occasion, there is no room for mistakes or misunderstandings in this school, understood?" Cat took the lead again, dropping her well prepared speech.

Most of the students in the room nodded in response.

"Let me remind you that your badge can be revoked at anytime, if the headmaster or the professors think it's necessary, take Mr. Jones into account, he's only one clever word away from losing his recently gained privilege and still manage to stand there in the corner with his head held high and a smirk on his conceited pretty face," Regina warned everyone, doing her best to stop herself from wrinkling her nose in disgust, because of the mere presence of Killian Jones in the prefect's cabin.

She diverted her gaze from the presumptuous boy, before she revoked his badge unfairly because of an arbitrary reason like breathing to loud, or his heart beating too fast or simply existing. Her eyes automatically fixated in a certain Gryffindor blonde girl, she smiled openly at her only sight. The blonde smiled back at her.

"That being said, you must now reunite with the head boy and head girl from your respective houses to get the rest of the information in regards to your obligations and responsibilities," Cat talked again, " they will also give you the new passwords to your house's common rooms and to the prefects' special common room.

Each houses' prefects reunited with their house head boy and head girl as requested, soon all of them had the required information.

The ride to the school was barely half way, when they found themselves free to do what they wanted before their arrival to the castle. The sixth and seventh year prefects started talking between them, while all the new prefects stood by their own in the cabin some of them talking with their own house's peers like Emma and Graham, Killian had tried to talk with Lena but she just rolled her eyes and leaned on her seat to observe the rest of them, ignoring him completely. Belle talked with her house partner Winn Schott for a while and now both of them were reading quietly on a seat. Kara by other hand was enjoying the open food trolley the school offered them, accompanied by her friend Neal Cassidy, she also interrupted her sister's conversations now and then, with her mouth ungracefully filled with still moving chocolate frogs, trying to escape her mouth.

"Enjoying yourself Kiera?" Professor Grant asked approaching the trolley from behind the blonde.

Kara turned her face around to look at the woman, with a chocolate frog enclosed in her lips fighting its way out, unsuccessfully, she quickly stuffed the chocolate animal in her mouth mercilessly and turned her face away again embarrassed. She could undeniably feel all her blood running to her cheeks fast, as undeniable and palpable as she could feel Catherine Grant's breasts now brushing against her back in the woman's attempt to reach a box of Bertie Bott's every flavour beans over her shoulder from the trolley.

Where was Neal Cassidy when she needed him most? Kara pleaded internally for a way out of this situation, but it never came.

"Yes ma'am," she mumbled in response.

"I know you are, sweetheart," she whispered flirtatiously in her ear, while pressing her body against her back a little less subtly.  

Kara's face became impossibly redder if that was possible. Was it just her, or professor Grant had just flirted with her? Being fair, she was basically blocking completely the food trolley with her body, but she also had to admit that that had been anything but an innocent touch.

When Cat walked away from the food trolley with her box of jelly beans, Kara scanned the room quickly, nobody seemed to have noticed what had just happened and she finally found his friend Neal playing the clown surrounded by her sister's friends, everyone laughed at his jokes. Kara let herself fall over one of the seats in the back, where no one could see her, she laid on her back, covered her face with her hands and tried to answer the question repeating in her head: why this things always happened to her?

**Author's Note:**

> Okay guys this idea has been spinning around my head for a while, I divided the initial chapter in two parts because it was getting too long. Please tell me what do you think by far, this is my first crossover and honestly I don't know if I'm doing a good job.


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